Propane Tank-ard

[hpstoutharrow’s] new instructable is a neat idea on how to re-use those single use small propane bottles by turning it into an insulated canteen. Once the bottles are emptied through normal use, the safety valve is popped loose and allowed to vent. There are also comments on the article that suggest that the bottle be submerged to ensure all gas is gone, and we think that is wise too.

Once safe to work on, the bottom is cut open and the stem is cut off leaving a empty shell, a soda bottle is shrunk down by boiling water inside of it for a little bit, then is fit inside the propane bottle. The top of the soda bottle is held in place by an O-ring, the safety pressure hole plugged up and the whole thing is filled with spray “expand-o-foam” locking everything in place and adding insulation.

Though using a thermoplastic bottle as its liner does not invite hot beverages to the party, it seems to do the job just fine for cold drinks, and it makes for a interesting conversation piece out on the campground.

Great re-use of the canister! I don’t see the need for cutting out the bottom though. You could compress the bottle, feed it through the top opening, and then re-inflate it. For insulation, you are better off with no foam. A pure vacuum is one of a few things that is better than air. Just leave an air gap, and it’ll keep your drink cooler than the insulation foam. You could use a little of the foam at the neck and bottom to stabilize the bottle and seal it in, but less is more in this case.

Not exactly a true vacuum thermos but obviously will help keep heat or cold in.

How do you get the smell out? Propane has methanethiol in it and getting the smell (and therefore molecules) out of the tank may prove daunting. I also worry a little bit about the steel and what it may have in it and of course the safety angle (making SURE the tank is empty).

This is only sort of true. Undisturbed air is a great insulator. UNTIL the air starts to move. At all. Then air becomes a decent conductor of heat. ANY gap or potential for air movement pretty much kills it. The difference is pretty huge.

Safety while reworking anything steel and pressure tigh as originally shipped- Darwin Reports may be your moments of fame if you screw up ok? That being stated as overview? Common accepted rules of water displacement or other inerting means make this Hack not horribly dangerous if you’re careful. Same with “how” you do the cuts. Insulation? Dead ait “works” but Canned Foams are “more better” though home made Aerogel cold be a Hack Points multiplier? Sadly, most Aerogel’s are Hygroscopic to a fault. Rewelding or Epoxy sealing the shell after sealing the drink container from the interior first is a Very Good Idea no matter what insulation used. Including sealing the shell space back up and pulling a vacuum to make a DIY Thermos

The refill adaptors? They’re Darwin Baiting for several reasons. Look up the term “Ullage” and the expansion ratios for Propane. Compute the accuracy needed to keep your refill UNDER the MAX suggested fill of 80% tank interior. Overfilling makes a Hydraulic pressure bomb. Mitigated only by the safety valve. Prevented only by never overfilling a tank. That Pol>bottle adapting Hack is only as safe as the human using it. And the tanks intrinsically are “Less Safe” in the disposable models!

It’s why it’s unlawful in many places. as is TRANSPORTING a refilled tank.

I hold a MO state propane card. uh- expored recently- have to recert.. Means- I’ve had a few recerts. Yeah, that card and a few bucks gets me a cup of coffee. But- it’s still a credential that makes me “at risk” if I screw up as I am presumed to Know Better in some jurisdictions..

That safety valve “may” keep you from a tank rupture. but IT VENTS A CLOUD OF GAS HEAVIER THAN AIR. Caps SCREAM ain’t nearly as loud as the sound of someone burning to death in a fire ok?

Some things are STUPIDLY dangerous and not only risks Darwinating the mishandler- soon to be dead if they’re lucky- half charred if they’re not It exposes innocent bystandaders to the same pain. Lends new meaning to: The Stupid! It BURNS!

But, if you use basic caution- no one gets hurt and this Hack’s safe for the careful. As is refilling small tanks if you are risk aware. And only use them mindful of how and where..

If you call this TLDR? your recovery from burns tends to be a lot longer..

Good material source. IIRC, absent measuring it- that one of the larger Red Bull cans might be a nice fit for the Coleman Propane Hack’s interior:)

I saw an “Earthship” type wall that used the Blue Hobnailed “Bawl’s” bottles. as throughlights.

A good source for the empty propane bottles is local campgrounds and similar places that small BBQ users congregate. Often, there’s an issue with trashing the bottles in quantity. Fishing Lakes being an example of where lantern users will leave a few such tanks next to the empty beers.

Is possible. It is very brittle stuff and as you mentioned, hygroscopic. If you have the means to make aerogel, you PROBABLY have the means to use something other than this steel can shell to seal it in. Would be easier to make a vacuum shell though and as long as you could maintain that vacuum, a better insulator than even aerogel.

One commenter already mentioned the plastic soda bottle leaching nasty chemicals into the beverages. But even worse are the nasty chemicals in the expanding foam, which could in time either diffuse through the soda bottle and then into the contents, or break down the plastic bottle altogether.

This is a cool project, but potentially dangerous in a totally non-cool way.

@Oren Beck; You’re almost correct, but not quite. You’re confusing ullage with nominal pressure. With compressed LIQUIDS, it really doesn’t matter how full your container is so long as it can handle the maximum nominal pressure at a given temperature for said liquid. This applies to many things, though the most likely you’ll ever see are CO2 and propane. Let’s take propane for example – You fill the tank in the liquid state. As it sits, some of this boils into a gas – It’s a closed system, so the gas can’t go anywher – It pressurizes the system. As the pressure increases, the boiling point of the remaining remaining liquid increases. When a balance is reached, you’ve reached the nominal pressure of the system is reached. Whether it’s a 1, 10, 20, or 100 lb tank, they all are at the same nominal pressure – this is defined by the nature of the liquid in question. CO2 is a bit more complex, but in practice it’s pretty much the same. When I used to fill CO2 tanks, we never really worried about explosions provided they were up to spec – We worried about asphyxiation in a closed room and shortcharging the customer…The scale is only there to make sure you’re getting what you pay for, not necessarily for safety’s sake.

…As for legality – As per DOT regulations, it is illegal to TRANSPORT a refilled single-use tank. They are not rated or certified to be refilled, but this is not necessarily for safety reasons. Odds are your tank is not going to catastrophically fail – If it would, why would you have been able to buy it in the first place?

…On a side note, DOT regulations also stipulate that compressed gas cylinders be transported in the vertical position rather than the horizontal…That means that, yes, it is illegal to lay a 100lb propane tank in the back seat of your car. Does anyone care? No…But it’s something to keep in mind…

…The chemistries of compressed gasses are all different… For example, what I said with regards to nominal pressure have NO BEARING when it comes to oxygen or nitrogen – They simply don’t work that way (essentially non-liquid in any common situations), and acetylene (MAPP is special) is entirely differnet… Hydrogen comes with it’s own host of issues (embrittlement)…

…There’s more to get into, but this is enough for one post… Personal suggestion? Go all the way and use one of the blue pounders as the inner cell… If you can’t weld, I’ve been using home depot’s rosin-core pipe solder with varying degrees of success for quite some time – It seems to work all right for steel to copper, but I haven’t tested it with steel to steel yet.

” But even worse are the nasty chemicals in the expanding foam, which could in time either diffuse through the soda bottle and then into the contents, or break down the plastic bottle altogether.”

The comment about Urethane foam’s “nasty chemicals” and it “leaching through or reacting with the plastic” are unfounded; especially as far as being a safety concern.

Fully reacted polyurethane polymer, CAS # 9009-54-5 (CAS registry number), is chemically inert.[25] No exposure limits have been established by OSHA (Occupational Safety and Health Administration) or ACGIH (American Conference of Governmental Industrial Hygienists). It is not regulated by OSHA for carcinogenicity.

We come in contact Urethane foam in so many every day places. This foam is used in pillows, car sets, and insulated lunch bags. Also, Urethane finishes are approve for use on children’s wooden toys.

The use in the application should not be a concern. This inert foam is not even contactable in the finished product.